"construction Methods & Equipment" May 1957, Pages 218, 219, 221, 224 PA0 "The Boston Sunday Globe" -- May 4, 1958 "MDC Road To Ease Charles Traffic" PA0 "The Boston Sunday Globe" -- Feb. 21, 1957 "MDC Eliminating Memorial Drive Accident Producing Bottleneck" PA0 U.s. pat. No. 1,778,925 PA0 U.s. pat. No. 3,751,931 PA0 U.s. pat. No. 3,875,752 PA0 U.s. ser. No. 629,508, filed Nov. 6, 1975